Scoria (scientific name) is known as a kind of natural ceramics which are pyroclastic deposits made by burning clay at high temperatures due to volcanic activity. When a volcano erupts, the scoria is formed by the hardening of the first erupted lava. At this time, the lava mixed with the gas is ejected first, and the scoria with a porous structure containing numerous fine holes is created in this process.
In Korea, the scoria is found in Jeju Island, and it is called Song-ee or Song-ee stone according to the dialect of Jeju Island. The physical property of scoria is weak alkaline with pH of approximately 7.2 to 7.8 and is porous, and the scoria exhibits colors such as reddish brown, yellowish brown, black and gray depending on the mineral constituents commonly contained.
Meanwhile, 5α-reductase, which is present in male hormone reactive tissues such as sebaceous glands, hair follicles, prostate, and epididymis, is an enzyme involved in the reduction of testosterone, which is one of the male hormones, to dihydrotestosterone (DHT). It is known that testosterone is involved in the increase of skeletal muscle, spermatogenesis, and the like, and dihydrotestosterone is involved in acne, increased sebum, prostatic hyperplasia and the like in the relevant tissues (Diane et al; J. Invest Dermatol. 775-778, 1995. Bruchovsky, N et al; J.B.C. 243, 2112-2121, 1968). Additionally, in the sebum gland of the skin, testosterone is converted to dihydrotestosterone by 5α-reductase and binds to a receptor protein in the cytoplasm to enter the nucleus and activate sebum gland cells and thus promote differentiation, thereby hypersecreting sebum in the sebum gland (Diane et al; J. Invest Dermatol. 105; 209-214).
In this regard, the present applicants have disclosed in Korean Patent Publication No. 1415996 that the scoria effectively inhibits the activity of 5α-reductase and thus has effects related to sebum control, the contraction of hair pouch and skin troubles.
In addition, it has been known that since the scoria contains a large amount of natural minerals and its own far-infrared emissivity is high, it has physical properties such as superior antibacterial activity and excellent deodorizing property. Also, it is a trend that since the scoria contains a large amount of natural minerals, the utility of scoria is increasing as a variety of cosmetic materials for skin moisturizing, the contraction of hair pouch, washing, antibacterial, and the like
The scoria is a porous material with a large particle size, which is a kind of pyroclastic deposits, but, the scoria is usually crushed into small particles and added when used as a cosmetic ingredient. However, if the scoria is crushed into micro size for cosmetic material, the porous structure is destroyed and the sebum absorption performance is lost. Also, due to the crystalline structure, because a disadvantage of the rough feeling of use cannot be avoided, there is a need for a porous composite powder structure with excellent sebum absorption performance without the scoria powder being directly exposed to the skin.